486 



SINCLAIR— ENTELODONTS FROM THE 



concave. Transversely, the process is convex externally in both 

 directions, and slightly concave longitudinally and transversely on 



Fig. i6. Scaptohyus altidens gen. et sp. nov. Holotype, No. 11161. Crown 

 view of the upper premolars of the right side, one third the natural size. 



the inner surface. It is 139 mm. wide across the maximum lateral 

 expansion. 



Fig. 17. Scaptohyus altidens gen. et sp. nov. Holotype, No. 11161. Crown 

 view of the left lower premolars and molars, one third the natural size. 



Megachcerus sygomaticus Troxell. 



No lower jaw is associated with the type skull of this form (No. 

 10008, Yale Palasontological Museum). Fortunately, a somewhat 

 better preserved skull in the Princeton collection, No. 11 156 (Figs. 

 18, 19), with a card-index record in Mr. Hatcher's handwriting 

 stating that it was found in the Protoceras beds south of White 

 River by the Princeton Expedition of 1894, has the right half of the 

 lower jaw preserved, bringing out additional characters for the sep- 

 aration of Megachcerus from its contemporary Pclonax. 



Close checking of the Princeton specimen with Mr. Troxell's 

 description^^ fails to show differences which can be regarded as of 

 more than individual or, perhaps, sexual value. The most striking 

 of these is the thickening of the distal end of the dependent malar 

 process to 30 mm., the thickening lengthwise of the central part of 

 the flange to 27 mm. by the development of a longitudinal convexity 



1^ Loc. cit., p. 433 and following. 



% 



i 



